Have you considered a quiet, custom built PC instead of a straight server?
I just bought a PC that'll easily hold 4 hard drives. The drive chassis's come with silicon holders to dampen noise.
You can then easily have installed top notch (and quiet) system and CPU fans for not much money.
Throw in some real fast and dirt cheap DDR3 Ram
And use SSD hard drives - they're completely silent. And fast.
The other option would be to drag a network cable to somewhere away from your desk and park the machine in another room. My two servers at home go in the basement.